1. Field of the Invention
The present invention relates to a damping intermediate pillar and a damping structure using such a damping pillar intended to absorb an input vibration energy or, especially, a horizontal force in framed structures and various other structures of buildings.
2. Description of the Related Art
The conventional techniques in this category include the following (1) to (7):
(1) Japanese Unexamined Patent Publication No. 2000-274108 relating to a structure of a viscoelastic damper coupled directly to the beams of upper and lower floors, (2) Japanese Unexamined Patent Publication No. 2000-54680 relating to a detailed structure for installing a viscoelastic damper on the beams of upper and lower floors, (3) Japanese Unexamined Patent Publication No. 2000-73605 relating to the surface shape of a laminated steel plate for a viscoelastic damper, (4) Japanese Unexamined Patent Publication No. 2000-73608 relating to a technique for coupling a viscoelastic damper, (5) Japanese Unexamined Patent Publication No. 2000-73609 relating to a technique for coupling a viscoelastic damper, (6) Japanese Unexamined Patent Publication No. 2000-73610 relating to a technique for coupling a viscoelastic damper, and (7) Japanese Unexamined Patent Publication No. 2000-73611 relating to the reinforcement around a viscoelastic damper.
Of the conventional techniques described above, an explanation will be given of a case in which the horizontal vibrations acting on the beams of the upper and lower floors are attenuated by being transmitted to a viscoelastic damper through an intermediate pillar, with reference to FIGS. 23A and 23B. In FIGS. 23A and 23B, beams 3a, 3b of the upper and lower floors and pillars 1 are coupled to each other by pillar-beam joins 2, and the beams 3a, 3b of the upper and lower floors are coupled to each other by a damping intermediate pillar 4 having a viscoelastic damper 6 at an intermediate portion thereof, thereby making up a structural frame of a building.
Specifically, the damping intermediate pillar 4 is divided into upper and lower portions, i.e. an upper damping intermediate pillar portion 4a with the upper end thereof fixed to the beam 3a of the upper floor and a lower damping intermediate pillar portion 4b with the lower end thereof fixed to the beam 3b of the lower floor. Also, the upper and lower damping intermediate pillars portion 4a, 4b are fixed with inner and outer steel plates 5a, 5b, respectively, which are superposed one on the other in spaced parallel relation to each other. A tabular viscoelastic member 5 of a predetermined thickness is arranged in the space between the superposed parallel steel plates 5a, 5b for holding the upper and lower damping intermediate pillars 4a, 4b. The tabular viscoelastic member 5 is held and fixed by adhesive thereby to make up a viscoelastic damper 6.
Assume that the structural frame of a building having the damping intermediate pillar 4 described above vibrates in an earthquake and a horizontal force is applied to the beams 3a, 3b in the direction of arrow in FIG. 23B. The particular horizontal force is transmitted to the viscoelastic member 5 from the beams 3 through the upper and lower damping intermediate pillar portions 4a, 4b. The horizontal force is attenuated by the viscoelastic member 5, while the pillars 1, the upper and lower beams 3a, 3b and the damping intermediate pillar 4 are deformed as indicated by dotted lines in FIG. 23B. In this way, the vibration is attenuated gradually.
In the case where a structural frame of a building is designed with a viscoelastic damper built in an intermediate pillar, the horizontal force due to an earthquake of an assumed predetermined magnitude and the damping capacity of the building are determined by calculations. In a manner to meet this condition, a viscoelastic damper having an attenuation capacity of a predetermined value determined by the material, size and thickness (sectional area) of the viscoelastic member is fabricated and built in the intermediate pillar. The conventional join structure between the upper and lower end portions of the damping intermediate pillar and the upper and lower floor beams, however, poses the following problem as it lacks the strength of endurance of the join between the damping intermediate pillar 4 and the upper and lower floor beams 3a, 3b against the horizontal force which may be exerted by an earthquake.
Specifically, in FIG. 23B, the damping action of the viscoelastic damper 6 is transmitted from the damping intermediate pillar 4 via the beams 3a, 3b to the pillar-beam joins 2 to damp the vibration of the building. In view of the fact that the upper and lower end portions of the damping intermediate pillar 4 are fixedly coupled simply by bolts or welding to the beams 3a, 3b of the upper and lower floors, however, the join strength is not sufficient against an earthquake of a comparatively large magnitude. As a result, the joins 9a between the damping intermediate pillar 4 and the beams 3 are inconveniently liable be broken before the damping function is exhibited.
The object of the present invention is to provide a novel damping intermediate pillar and a damping structure employing such a damping intermediate pillar which solve the problem of the prior art described above.